Front driver and passenger airbags have saved numerous lives and reduced injuries from severe frontal crashes. These airbags have been proven to work effectively on the roads for both belted and unbelted occupants, even though they are supplementary devices to safety belts. They are designed to absorb kinetic energy during crashes in such a way that the occupant decelerates smoothly by cushioning from the inflated airbags.
In order for the airbags to protect the occupants properly, the airbags should be fully inflated fast enough to be in position in front of the occupants during the crash. However, this fast inflation sometimes causes serious injuries to the occupants, especially to out-of-position occupants. For example, the occupant can move forward and get very close to the airbag during emergency braking before the crash, and then can be injured or killed by the fast-inflating airbag. Infants riding in a rear facing child seat (RFCS), children, and small size adults are more vulnerable to the risks.
The National Highway Traffic Safety Administration (NHTSA), a government agency, has proposed a rulemaking that sets a new performance requirement and test procedures for advanced airbag systems. The intent of this rulemaking is to minimize risks caused by air bags to out-of-position occupants, especially infants and children, and also to improve occupant protection provided by airbags for belted and unbelted occupants of all sizes. The new rule for advanced airbags applies to about 20 percent of 2004 model year vehicles and all applicable vehicles of 2007 model year and afterward.
The advanced airbag rule, in part, requires as an option to conduct low risk deployment (LRD) airbag tests with a 12-month-old infant dummy in a rear facing child seat, and dummies representing 3 and 6 year old children. If the dummies from the airbag deployment tests do not meet the injury criteria limits set by NHTSA, vehicle manufacturers can choose another option of suppressing the airbag when infants or children are present. This airbag suppression option, however, may not provide the benefits of airbag protection for infants and children. An occupant classification sensing system is currently used in order to detect the presence of infants and children, and thus suppress the airbag accordingly. However, this occupant classification sensing system not only adds cost to a vehicle, but can also lead to reliability problems.
There have been a number of prior art attempts to reduce the injuries caused by airbag inflation to a level that can meet the low risk deployment option. The prior art attempts have employed multiple chambers in a single airbag, a bag inside another bag, different ways of airbag deployment, different ways of airbag folding, different power splits between two chambers in a dual chamber inflator, etc. To date, however, none of these technologies has proven to work reliably enough to reduce the injuries of small children and infants in rear facing child seats to a level that can meet the injury criteria of the low risk deployment option while also protecting in-position adults during serious crashes. The neck, among an occupant's body parts, is especially vulnerable to serious injuries exceeding the injury criteria limits set by the regulation.